# HTTP Methods and Status Codes

> What each HTTP method promises, what each status code family means, and how to find the failing part of a web system from one response.

Canonical: https://codelivly.com/rooms/http-methods-and-status-codes
Last updated: 2026-11-15

| | |
|---|---|
| Level | Beginner |
| Category | Web |
| Lessons | 6 |
| Estimated time | 3 h 30 min |
| XP | 150 |

Go past the list of methods and codes to the rules behind them. You learn which methods are safe and idempotent and why browsers, proxies and crawlers rely on that, how GET, HEAD, OPTIONS, POST, PUT, PATCH and DELETE behave on a real API, and what the 2xx, 3xx, 4xx and 5xx families tell you. Every lesson uses curl against the Fernhill Outdoors lab shop. The room ends with a guided lab in which you diagnose a broken API after a deploy from its status codes alone.

## Lessons

1. Safe, Idempotent and Unsafe Methods (30 min)
2. GET, HEAD and OPTIONS: Reading Without Changing (30 min)
3. POST, PUT, PATCH and DELETE: Changing Things (35 min)
4. The 2xx and 3xx Families: Success and Redirects (35 min)
5. The 4xx and 5xx Families: Whose Fault Is It (35 min)
6. Guided Lab: Diagnose a Broken API from Its Status Codes (45 min)

## Related

- [Learning path: Web Fundamentals](https://codelivly.com/learning-paths/web-fundamentals)
- [All rooms](https://codelivly.com/rooms)